Development And Analysis Of Solar-skylight Spectroradiometer

As an effective device for remote sensing to detect characteristics of solar irradiation,atmospheric transmittance and aerosol content,solar radiometer provides continuous and reliable radiation distribution and atmospheric optical properties for environmental detection and meteorological sciences.Since solar energy is selectively absorbed and scattered by atmospheric molecules in transmission,the radiation distribution on the ground characterizes the absorption information and composition content of atmosphere.Refined solar irradiation information not only has a significant impact on ecological environment assessment,photovoltaic resource development and other research fields,but also helps to improve people's understanding of radiative transfer.At present,integral solar radiometers generally have the shortcomings of insufficient spectral resolution and limited data information,and gradually cannot satisfy the needs of scientific research for refined observation of spectral irradiation.Therefore,this paper proposes a whole-sky irradiation measurement scheme for obtaining refined solar spectrum from visible to infrared band,and designs a spectral radiometer with two measuring modes:direct solar irradiation observation and diffuse sky radiation detection.The research content of this article is as follows:(1)This study proposes a solar-skylight spectroradiometer for obtaining solar spectrum range of 380?1100 nm,with spectral resolution of 0.1 nm.(2)In the instrument development,this paper designs the tracking light-path and spectrum measurement light-path.Based on the existing turntable structure of the research group,the servo system of the two-axis turntable has been upgraded.Then,the appliance of temperature control technology provides a constant temperature environment with heat insulation,air cooling and rapid homogenization for the probe cavity;(3)As for the control architecture,this study combines ARM chip of Cortex-A7 architecture and embedded Linux as master control unit.By introducing a properly configured communication protocol family(USB,TCP/IP,and UART),the built-in control software could realize distributed control of measurement components.The cross-platform program framework Qt is used to design graphical user interfaces for monitoring the operating status of the radiometer and displaying real-time spectrograms;(4)In the radiometric calibration,standard integrating sphere contributes to achieve absolute radiation calibration,and Langley method will determine the coefficients for direct-sun measurement,after which the instrument can realize the spectrum calibration in the whole band.The comparison between spectral radiometer,DTF sun-photometer,microwave radiometer and CART simulation verifies the reliability of radiation measurement system.What's more,we can further use radiation information of the characteristic waveband to retrieve other atmospheric parameters and optical characteristics.The experimental results show that:in terms of direct sunlight,the atmospheric transmittance measurement of spectral radiometer shows maximum relative error of 8%compared to that of the DTF sun-photometer.The relative error of the water vapor is within 10%compared to that of microwave radiometer.The experiments present that the performance of spectroradiometer is relatively accurate and stable;As for skylight scattering,compared to the traditional radiometer measuring specific band on a preset orbit,the spectral radiometer can measure the radiation distribution and fine spectral information of the whole sky.Spectral radiometer not only provides refined solar irradiation information,but also enriches the information channel for obtaining transmittance and atmospheric molecular content.